<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>md文本测试</title>
    <script src="http://apps.bdimg.com/libs/jquery/2.1.4/jquery.min.js"></script>
    <script src="https://cdn.bootcss.com/marked/0.3.4/marked.min.js"></script>
    <script src="https://linwalker.github.io/render-html-to-pdf/js/html2canvas.js"></script>
    <script src="https://linwalker.github.io/render-html-to-pdf/js/jsPdf.debug.js"></script>
    <script src="http://cdn.bootcss.com/highlight.js/8.0/highlight.min.js"></script>
    <link rel="stylesheet" href="https://sindresorhus.com/github-markdown-css/github-markdown.css">
    <style>
        
    
    #edit {display: flex; justify-content: space-between;}
    #content {width: 49%;float: left;height: auto;}
    .button {
        color: #fff;
        background-color: #009a61;
        border-color: #008151;
        padding: 0 13px;
        font-size: 14px;
        border-radius: 4px;
        margin: 10px;
    }
    #show{width: 50%; border:  1px solid  #ddd; padding: 50px; box-sizing: border-box;float: left;height: auto;}
    
    .hljs-comment,.hljs-quote {
     color:#989498
    }
    .hljs-variable,.hljs-template-variable,.hljs-attribute,.hljs-tag,.hljs-name,.hljs-selector-id,.hljs-selector-class,.hljs-regexp,.hljs-link,.hljs-deletion {
     color:#dd464c
    }
    .hljs-number,.hljs-built_in,.hljs-builtin-name,.hljs-literal,.hljs-type,.hljs-params {
     color:#fd8b19
    }
    .hljs-class .hljs-title {
     color:#fdcc59
    }
    .hljs-string,.hljs-symbol,.hljs-bullet,.hljs-addition {
     color:#8fc13e
    }
    .hljs-meta {
     color:#149b93
    }
    .hljs-function,.hljs-section,.hljs-title {
     color:#1290bf
    }
    .hljs-keyword,.hljs-selector-tag {
     color:#c85e7c
    }
    .hljs {
     display:block;
     background:#322931;
     color:#b9b5b8;
     padding:0.5em
    }
    .hljs-emphasis {
     font-style:italic
    }
    .hljs-strong {
     font-weight:bold
    }
    
    </style>
</head>
<body id="edit">
<div><button id="download" class="button">下载html</button><button class="button" id="downloadPdf">下载PDF</button></div>

<textarea  id="content"></textarea> 
<div id="show" class="typo markdown-body">content</div>

<script>
    marked.setOptions({
        renderer: new marked.Renderer(),
        gfm: true,
        tables: true,
        escaped : true,
        breaks: false,
        pedantic: false,
        sanitize: false,
        smartLists: true,
        smartypants: false,
        highlight: function (code, lang) {
        return hljs.highlightAuto(code).value;
      }
    });

    $("#content").on("input  propertychange", function() {
        var val = $(this).val();
        $("#show").html(marked(val));
    });


    function downloadFile(fileName, content){
      var aLink = document.createElement('a');
      var blob = new Blob([content]);
      var evt = document.createEvent("HTMLEvents");
      aLink.download = fileName;
      aLink.href = URL.createObjectURL(blob);
      aLink.click();
    }



    $("#download").click(e=>{
      var tpl = new Template($('#tpl').html());
      var s = tpl.render({
          title: "markdown",
          style:$("style").html(),
          content:$("#show").html()
      });
      downloadFile("markdown.html",s);
    });


  function Template(tpl) {
      var
          fn,
          match,
          code = ['var r=[];\nvar _html = function (str) { return str; };'],
          re = /\{\s*([a-zA-Z\.\_0-9()]+)(\s*\|\s*safe)?\s*\}/m,
          addLine = function (text) {
              code.push('r.push(\'' + text.replace(/\'/g, '\\\'').replace(/\n/g, '\\n').replace(/\r/g, '\\r') + '\');');
          };
      while (match = re.exec(tpl)) {
          if (match.index > 0) {
              addLine(tpl.slice(0, match.index));
          }
          if (match[2]) {
              code.push('r.push(String(this.' + match[1] + '));');
          }
          else {
              code.push('r.push(_html(String(this.' + match[1] + ')));');
          }
          tpl = tpl.substring(match.index + match[0].length);
      }
      addLine(tpl);
      code.push('return r.join(\'\');');
      fn = new Function(code.join('\n'));
      this.render = function (model) {
          return fn.apply(model);
      };
    }

$("#downloadPdf").click(e=>{
    html2canvas(document.body, {
      onrendered:function(canvas) {

          var contentWidth = canvas.width;
          var contentHeight = canvas.height;

          //一页pdf显示html页面生成的canvas高度;
          var pageHeight = contentWidth / 592.28 * 841.89;
          //未生成pdf的html页面高度
          var leftHeight = contentHeight;
          //页面偏移
          var position = 0;
          //a4纸的尺寸[595.28,841.89]，html页面生成的canvas在pdf中图片的宽高
          var imgWidth = 595.28;
          var imgHeight = 592.28/contentWidth * contentHeight;

          var pageData = canvas.toDataURL('image/jpeg', 1.0);

          var pdf = new jsPDF('', 'pt', 'a4');

          //有两个高度需要区分，一个是html页面的实际高度，和生成pdf的页面高度(841.89)
          //当内容未超过pdf一页显示的范围，无需分页
          if (leftHeight < pageHeight) {
          pdf.addImage(pageData, 'JPEG', 0, 0, imgWidth, imgHeight );
          } else {
              while(leftHeight > 0) {
                  pdf.addImage(pageData, 'JPEG', 0, position, imgWidth, imgHeight)
                  leftHeight -= pageHeight;
                  position -= 841.89;
                  //避免添加空白页
                  if(leftHeight > 0) {
                    pdf.addPage();
                  }
              }
          }

          pdf.save('content.pdf');
      }
    })
}); 
    


</script>

<script id="tpl" type="text/plain">
 <html>
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1, minimal-ui">
<title>GitHub Markdown CSS demo</title>
<link rel="stylesheet" href="https://sindresorhus.com/github-markdown-css/github-markdown.css">
<style>
    @media (min-width: 768px) {
        .markdown-body {
            box-sizing: border-box;
            min-width: 200px;
            max-width: 980px;
            margin: 0 auto;
            padding: 45px;
        }
    }
</style>
</head>
<body>
<article class="markdown-body">
{content}
</article>
</body>
</html>
</script>

</body>
</html>